Open Source Firmware on brand name Radios

[alibenpeng]

Hi,

I'm currently using openTX on a 9x which works great, but compared to even mid priced transmitters like the Devo 8s or the Spektrum DX series the 9x hardware feels just cheap. Right now I'm considering buying a Devo 8s, but I was wondering if these (the various 9x variants and the Devos) were the only hardware options if one insists on open source firmware.

So my questions are these:

1. Are there any known OSS projects for other hardware platforms like Futaba, Graupner, Jeti, etc.?

2. If so, can anyone provide links, as I haven't found any?

3. If not, what are your guesses as to why there aren't any (Are people reluctant to crew up their $$$ TX or is the original firmware just so good)?

4. Would OSS on higher priced radios possible/practicable, i.e. what hardware is in them, in terms of microcontrollers? If it's also just same old AVR/PIC/ARM architectures, porting OpenTX or Deviation should be at least possible, if not easy.

5. And finally, is it even worth the effort or is the Devo 8s the last remote I'll ever need (and yes, I realize this is a forum devoted to OpenTX and derivates, but I'm just asking opinions here)?


Thanks for your input!

Cheers,

Ali

[Kilrah]

1) Not that I know of.
3-4) Expensive entry point, more complex hardware, sometimes custom chips with no available doc = complicated reverse-engineering... For example a Jeti DC16 contains at least 8 separate MCUs, with the need to understand what each of them does and how they're interconnected, and require writing separate custom firmwares with appropriate inter-mcu communication for each of them. Would take years (and I can't understand why they've gone this route, it's likely a maintenance nightmare).

5) IMO not worth the effort at all to spend months reverse engineering brand name radios with no manufacturer support, where by the time we're done the model is discontinued and work needs to start over on the replacement. Especially as with HK and their 9XR, and FrSky with the Taranis and upcoming higher end models we now get full manufacturer support and have a say in the actual hardware design too. Much more efficient and interesting to work that way in a leading position where we can concentrate on new features rather than lose our time reverse engineering 3rd-party hardware just to try and catch up without adding anything new.

So basically with the Taranis and 9XR-Pro you've now got a couple of radios that were "designed for the firmware" as much as the opposite, and there's much more to come. And already with much better hardware than a 9x.

[Rob Thomson]

100% agree

[alibenpeng]

I see your point.

Now with that out of the way, the remaining options are OpenTX and Devention. I assume that you probably favour the openTX platorms over the Devos (after all, this is an openTX forum), and I've come to know and like openTX myself, too. One thing I particularly liked in the beginning was the ability to support different protocols via modules. Ironically it's the exact same thing that is driving me away now. I've built two transmitter modules for the 9X and while writing the code for them, I got increasingly annoyed by the fact that I had two microcontrollers talking to each other via PPM. My point being, connecting the raw transceiver modules (e.g. nrf24l01 or a7105) directly to the TX's main chip via SPI has it's advantages over a 50+ year old protocol designed to transmit analogue values. Come to think of it, that's even worse than MIDI

But seriously, that's the one thing keeping me from considering the Taranis or the 9XR (Pro) any closer. Especially the Taranis seems like a very nice TX, but is there a way to connect more than the stock transmitter module internally via SPI and is there support for this in openTX (planned)?

[jhsa]

(after all, this is an openTX forum),

No it's not

This is an OpenRC Forum.. It's not only about openTX. There are other firmwares being discussed here too like er9x and ersky9x, among other projects directly and not directly related to any of the firmwares.

I'm writing this just that people don't get the wrong idea and really think that only openTX is being discussed here

João

[Kilrah]

I got increasingly annoyed by the fact that I had two microcontrollers talking to each other via PPM.

Psychological gripe I guess.
I use the Taranis' internal module for 90% of my uses. For my Spektrum-equipped UMX models I use a DSM module, it may communicate through an outdated PPM signal but who cares, it works and doesn't introduce any drawback I could notice.

Directly SPI-driven RF module in a commercial open source product would cause issues regarding certification as everybody could easily tamper with the RF output.
As it is you won't have SPI, but digital serial data can be sent through the PPM pin (as is done for the FrSky module), and the telemetry bidirectional serial port is also available in the module bay. So nothing forces your module to communicate with PPM, you could implement PXX on it and set the radio as if it was an XJT, or you could implement whatever additional protocol you want on both sides.

[alibenpeng]

(after all, this is an openTX forum),

No it's not
João

Even better.

BTW, by "openTX forum" I didn't even mean openTX specifically, but rather the whole 9x/taranis ecosystem. I just happened to stumble upon openTX first and stuck with it, so I used it as a synonym.